Pantograph



Im/ENTOR. L. R/dgway ATTORNEYS.

sept. 18, -19:28.

L. RIDGWAY PANTOGRAPH Filed Aug. 4, 1927 Patented Sept. 18, 1928.

LAT BIDGWAY, OF CANON, GEORGIA.

PANTOGRAPHI. f

Application ledfAugust 4', 1927. Serial No.' 210,642.

Thisinvention relates to improvements in pantographs, and it has for-itsobject the provision of a device of simple and sturdy construction; moreparticularly, it is sought to 5 provide means for transmitting themovement of the tracing stylus to the reproducing stylus so that lostmotion and slipping of the driving parts is reduced to a minimum. Themeans employed for the purpose is described in detail hereinafter,pointed out in the appended claims and illustrated in the accompanyingdrawings. E

the accompanying drawings,-in which similar reference characters'designate corre- !5 sponding parts:

Figure 1 is a plan view of a. embodyingthe invention. Y

Figures 2, 3, 4, 5 and 6y are, respectively, detail sectional views onthe lines 2*-2, 3-3,

Referring to the drawings in detaihthe frame of the machine is of'anelongated'rectangular formation and comprises the longitudinal members-10 joined at their ends by 25 the cross members 11` to form a rigidstructure. Extending across the vunderside ofthe frame is the pivotmember 12 positioned so that Vone-third of the length of the frame is onone side of said member and'two-thirds is on the other side. Projectingfrom the under side ofthepivot member is the lug 13 in which is mountedthe pin 14 to be forced into the drawing board or othersupport when thedevice is operated. This pin, seated in the drawing board, forms thepivot'about which the frame is turned. At the ends of the frame aremounted the rollers 15 journaled in the brackets 16 attached to thecorners of the frame. These rollers travel on a 40 plane including thelower end of the lug `13 and in practice this'plane is formed by thesurface of the drawing board on which the devicefis mounted. With thepin14 journaled inthe drawing board the frame can be freely oscillatedabout the pivot so formed, the rollers 15 riding on the board carryingthe frame. and maintaining it in its parallel relation `to theboard. p

'Extending across the upperv part of the 5oV frame and parallel to thepivotmember 12 is pantog-raph the uppermember 17 secured at its ends tothe yspacing blocks 18, secured in turn to the loni gitudinal members10. These members, so connected, form a transverse frame in thelongitudinal main frame.v Mounted in tho 5. transverse frame is thepulley 19v having concentric rims 20 and 21 with the latter of twice thediameter of the former. The pulley is carried by the integral' sha-ft 22journaled at its lower end in the pivotmember 12 and at, its upper endin the set-screw 23 threaded in A the upper member17 of the transverseframe.V By backing out the set-screw the pulley can be readilydismounted, The axis of the double-rimmed pulleyis coincident with thepivotal axis of the main frame.

Mounted. in the main frame on opposite sides ofthe transverse frame arethecarj riages 25 and 26 of like construction. Each, carriage comprisesa frame of H-shape formation having grooved rollers 27 journaled in theextremity of eachV arm. Each carriage travelsbetween the longitudinalmembers 10 of the main frame with the grooved rollers 27 engaging thetracks 28 extending along the li5 inner faces of the longitudinalmembers'. In: each carriage is centrally located a stylus 29frictionally held for vertical adjustment therein. The axes of the twostyli and of the double-rimmed pulley are in the same vertical plane andthese relative positions are maintained irrespective of the travel ofthe carriages in the main fram Y v In the cross-pieces 11 at theopposite ends of the main frame are journaled the `pulleys 30 and 3l,respectively. Looped around the idlerpulley 30 and the rim 2O of shorterdiameter of the double pulley is the band32 attached at its ends toopposite sides'of the carriage 25. Likewise, a band 33 .is looped aroundthe idler pulley 31 andv the rim 21 of greaterl diameter of they doublepulley and j its ends are attached to opposite sides of the carriage26.` The pulley 30 andthe rim 20 are of the same diameter, as'arethepulley 31, and the'rim 21, to maintain their respective bands inlongitudinal parallel relation Vto the main frame. Each band is undertension to provide frictionalA engagement between it and the pulley rimwith 'which it is engaged, 10

so that the drive of one will be imparted to the other without relativeslip. It is to be observed that the length of the guideway for thetravel of the carriage 25, which is connectthe distancel between theaxial centeroi` the pulleyand the axial center of the carriage l,

25, the axial centers of the carriages being indicated by theirrespective Styli. VConso quently, the proportionate travel of the twocarriages on the supporting frame is the same'` as the proportional1relation ofthe diameters otthetwo rimsofthe double pulley that is, asone to two.

From the foregoing it is obvious that. if the carriage 25 isrmoved ineitherv direction on its guideway, there will be a correspondingmovement ofthe carriage 26 on its guideway, but the lattcrl will traveltwice thedistance travelled by thev former. Also, the movement of thecarriages will be in opposite directions; lfor an instance, if thecarriage 25 is moved to the left, as shown in Fig. 1, the carriage26.'will move to the right.` 'The proportional travelof the twocarriages may be varied by substituting for the double pulley, otherpulleys with rims of differentlproportionate relations. SuchVsubstitution is facilitated-by the adjustable setfscrew 23.`

yIn the operation of the device, for anvers` ample, to reproduce thegiven triangle a, b, c, enlarged to twice the size, asat d, e, f,the-paper-with the given triangle displayed there` on is affixed to adrawing boardin the usual manner. The pantograph is then mounted on theboard by forcing the pin 14 into Vthe same so that the Wheels 15ridethereon; Itis positionedso that the given triangle iscontainedwithin the-field of travel of the car-l riage 25 as the deviceis turned on 'its -pivot formed :by the Vpin 14 journaled in the board.

The main frame is turned on its pivot and;

the carriage 25 is moved on vits guideway to position thestylus 29mounted in said carriage directly` abovethe `angle a of the giventriangle.. Then both Styli 29 are forced" downwardly into contact withthe paper. For convenience,.the stylus mountedin the carriage 25 may bedesignatedas the tracing stylus and the one in the carriage 26thereproducing stylus, the latter being a pencil `or apen; also thecarriages 25 and `26 may be Vrespectively designated as the tracing andreproducing carriage.`

After the device has been initially positione'd, the tracing stylus ismoved along the line aff-b. This movement of the"` tracing stylus causesthe device to turn on its pivot lliand the tracing carriage to move onthe yguideway, outwardly toward the left end of the frame as shown inFig. 1. As the tracing carriage 25 moves along tne guideway the band orbelt 32 is drawn the same distance around the Vpulley rim 20. Throughthe frictional engagementof the band with the pulley rim, the doublepulley is rotated and the rim 21 draws the band wtopropel the reproducincarriage 26'along the guideway. Y

linefd-fibeing twieethe'length of the yline a-1-b.. Likewise, asthetracingstylurssucoessively followsv the lines b`o ando-a ofthe giventriangle the reproducing` sytlus successively format e lines. fL-e'an`e-dito comeV plete the enlarged reproduction'oithegiven` triangle.While the example given of:` the i operation of the device is a simpleone yet itfisA particularly adapted to thereproduction of` com licatedwork, such as maps.

hat Ilclaim is:

1. In a .pantograph,` the combination of@` an elongated frame having alongitudinal guideway', means for pivoting the frame atan intermediatepoint, a carriage,mounted in each endiofithe frameto travel intheguide-l way with the carriages Aonopposite rsides of Y the pivotalpoint; of the ia'me, a stylus' mounted in each i carriage, a.doubleimmed pulley mountedion the frame-.with its, axis: alinedi withthe pivotal axisoffthe frame,

the rims of1tl`1epulliey` having diameters in proportional relation to.eachother, and bands respectively connectedwiththe oppo` site carriagesand, each band being looped aroundone of the rima` ofithe double'pulleyso that thetravelof` one offthe carria es 1s transmittedto theother-carriageiwit the--` travel f of, the carriages in proportional`rei lation.

2.. In a pantograph, the combination Vof an;r

elongated frame having a lon itudinal guideway, means for pivotingrthenrame at.`

an intermediate part, carriages: mounted inj Vthe frame to travel intheguideway on oppo-L.;

site sides of the `pivotal pointfof the frame,.l

a stylus mountedin each carriage, a double:

rimmed pulley mountedinithe frame'with its axis coincident with lthepivotsA of.` the frame, and bands in` `opposite extension` looped aroundthe. rims of t Vpulley andere spectively connected with the oppositecar-v. Y

1251` moved on the guideway aproportional travel.

riages so that when one of thelcarriages is is transmitted to the othercarriage.

3. In a pantograph, thecombination Otan elongated frame having. alongitudinal guideway, .idler pulleysmounted in the frame at malezas? yc 3 opposite ends of the guideway7 means for tension looped around therims of the doupivoting the frame at an intermediate part, ble-rimmedpulleys and the idler pulleys and l0 carriages mounted in the frame totravel in respectively connected with the opposite carthe guideway onopposite sides of the rivotal riages so that when one of the carriagesis 5 point of the frame, a stylus mounted 1n each' moved on the guidewaya proportional travel carriage, a double rimmed pulley mounted in istransmitted to the other carriage. the frame with its axis coincidentwith the In testimony whereof I alx m signature. pivot of the frame, andbands in opposite exn LAT RI GWAY.

